The present invention generally relates to animal containment systems. Specifically, the invention is an apparatus and method for restricting an animal""s movement without a fence or invisible barrier. More specifically the invention relates to controlling an animal""s movement using a dynamically changing perimeter defined by a GPS receiver, which is expandable to encircle the animal if the animal breaches the perimeter, giving the animal a return path to the original perimeter.
Conventional and electric fencing is commonly used to control the location of animals. Barrier fencing, which physically blocks the movement of the animal is most frequently used to confine both domestic pets and farm animals. Physical electric fencing, which uses an electric shock to discourage contact with the fence, is typically used to confine commercial livestock. The purpose of an electric fence is to keep farm animals within an area, or to prevent undesired animals from entering property. High voltage electrical impulses are applied to a xe2x80x9clivexe2x80x9d fence wire by an energizer. This impulse lasts only thousandths of a second but is repeated every second or so. An animal, which strays into contact with the live wire, completes a circuit between the live wire and the soil. The result is an electric shock sufficiently unpleasant to cause the animal to move rapidly away from the fence before the next electrical impulse. After a few encounters, animals learn not to touch the live wire or approach the fence too closely.
In its simplest form, an electric fence comprises a single live wire elevated above the earth by a suitable means of support and electrically insulated from the earth. This basic electric fence arrangement relies on moisture in the soil to act as a conductor of electricity from the animal back to the energizer. When an animal makes contact with the live wire, the electrical impulse is conducted through the muscles of the animal, down into its legs and into the soil and through the moisture in the soil back to the energizer. This completes the electrical circuit.
An important disadvantage of electric fencing is the labor-intensive installation of the fence, which, depending on acreage, can require anywhere from a few to hundreds of man-hours. Another disadvantage is the physical presence of the fence on the property, which presents an electrical shock hazard to humans and can be unattractive. In addition, the fencing relies on peripheral elements such as the moisture in the soil in order to be effective, and may be subject to damage over time from environmental factors.
Recently, hidden electronic fences have gained popularity. Hidden fences are not physical barriers; but instead psychological barriers. Once installed, the animal will understand from experience that it cannot pass through the barrier without being disciplined/corrected. A receiver on the animal""s collar administers the correction. The correction is an electrical impulse similar to the impulse administered by the physical barrier fence. It is harmless yet is unpleasant enough that the animal will want to avoid the sensation in the future.
Installation of a hidden electronic fence involves burying a boundary wire around the perimeter of the property or whatever other area to which the user wants to restrict the animal""s movement. Each end of the wire is then plugged into a transmitter. Once the transmitter is switched on, it generates a signal from the wire. This signal activates the dog""s receiver whenever the dog comes close to the boundary wire. Activation of the receiver can trigger an audible sound to warn the animal, or if the animal is very close to the wire, an electrical shock.
An important disadvantage of hidden electronic fencing, similar to above-ground electric fencing, is the labor-intensive installation of the fence requiring trenching or other digging in order to install the boundary wire. Another disadvantage is that if the animal runs through the barrier, they have a distinct impediment to crossing that barrier again, as the receiver is indifferent to the animal""s direction of travel. Such xe2x80x9crun-throughxe2x80x9d is a common phenomenon with fast animals such as dogs, which may become distracted and violate the perimeter in an instant after being enticed by an attractive stimulus. For example, the dog""s predatory instinct may be aroused by a nearby animal, causing them to chase the animal without regard to the pending correction. After such run-through, the animal is confused or in a state of panic because it has strayed from the defined area, and may even be receiving unpleasant stimuli, but is unsure how to proceed or otherwise does not respond to the stimuli as desired. They are trapped outside of the area they are supposed to be in but may be presented with a definite disincentive to return. For example, as they approach the defined property, a warning tone may sound at their receiver, or they may receive a correction. Finally, the setting and determination of the perimeter""s boundaries can be complicated, for example, by driveways, and dependent upon a location to safely place the electrical wire.
Further advancements in the technology, which are able to determine the location of an object, have led to alternative means of animal control. The United States government has placed in operation a multiple-satellite global positioning system (xe2x80x9cGPSxe2x80x9d). A GPS receiver receives signals from multiple satellites in orbit, and calculates the position of the receiver based on the signal data. This method of location determination is well known and the positions provided can be within xc2x13 meters.
Livestock confinement systems have been developed which rely upon GPS to determine the location of a receiver attached to an animal as shown in U.S. Pat. No. 5,868,100. The system uses a combination of electronic animal ear tags and GPS receiver/transmitters to control the location of livestock. The system is comprised of a lightweight, battery-powered animal ear tag that provides an audible warning and electric stimulation in response to a radio frequency signal from a fixed transmitter. The ear tag is attached to the animal and the movement of the animal is controlled based upon the location of the transmitter unit. The system is designed to exclude animals from a defined area such a stream or wetland. The system compares the position of the animal""s receiver to a predefined boundary and administers a correction as the animal approaches the boundary. A system such as that of U.S. Pat. No. 5,868,100 may be more flexible than the buried wire systems since boundaries can be changed, but animals that cross the boundary may still be subject to continuous correction or otherwise be discouraged from returning to the desired location. There may also be limitations on the precision of boundary definition and location determination, which results in inconsistencies in the actual point at which the livestock are corrected. These limitations include the inability to take GPS coordinates rapidly enough to indicate the exact location of the subject at all times or the lag or error of GPS systems which can cause imprecise determination of actual receiver locations.
The ability to easily modify the restricted area is a significant advantage of GPS-based location control systems. This capability is used to control livestock grazing by easily reprogramming the restricted area to provide for maximum utilization of feeding range. Similar applications allow for monitoring by GPS systems of persons under house arrest, and their restricted area can be modified to allow for approved excursions, for example doctor appointments, as shown in U.S. Pat. No. 5,892,454. However, these applications, which allow perimeter movement based on a predetermined time or event, are limited in that they require operator intervention to program the alternative boundary.
Generally, typical GPS only systems provide at best a xc2x13-meter accuracy. For containment applications, accuracies of 2 meters or less are desired. Systems are available today that will achieve the necessary accuracy by utilizing a local differential transmitter, and reading another GPS band carrier signal. However, certain factors may prevent their use in a containment application. For example, the cost of such systems can range from over $1000 for a surveying receiver to over $3000 for a local transmitter. Other factors include present systems being too large for portable use, typically requiring large amounts of power resulting in short battery life, and having complicated user interfaces.
The present invention provides for animal containment through a system having a containment collar and GPS (Global Positioning System), RF (Radio Frequency), or INS (Inertial Navigation System) data or a combination thereof, to define the perimeter of a containment area. A receiver is mounted to the containment collar, or other apparatus worn by an animal, which contains positioning electronics, memory, and warning outputs. The user defines the perimeter by programming xe2x80x9cway pointsxe2x80x9d (positions on the perimeter) into the collar. The system provides an audible warning when the animal is within a user-programmable distance of the perimeter, and then provides an adjustable shock or other stimulus to the animal when the perimeter boundaries are exceeded. Upon perimeter violation and initial correction to the animal, the system dynamically changes the position of the boundary encompassing the animal""s prohibited position. Then the dynamic boundary may be gradually or incrementally changed so as to direct the animal toward the original perimeter. This creates an xe2x80x9camnesty alleyxe2x80x9d or a bubble/bulge in the perimeter so the animal is not continuously corrected and can go back within the original perimeter without further correction. The boundary may then preferably return to its original configuration once the animal is back inside the perimeter.
The present invention thus provides for an animal containment system that uses a GPS system to dynamically change the boundary, which may change in response to a breach of the perimeter by the animal, and then may rein in the animal to prevent the animal from further straying. For example, upon perimeter violation and stimuli, if the animal does not return to the defined area, the boundary would be reset to a boundary that encompasses the animal""s prohibited position. The invention thus provides for elimination of confusion or panic in an animal that has strayed from the defined area and is receiving unpleasant stimuli but is unsure how to proceed; dynamic boundaries that can be gradually or incrementally changed so as to direct an animal towards an original perimeter; global positioning satellite data to define a perimeter, the ability to program a series of GPS coordinates into a collar to define an area in which a animal may roam; to program a collar by walking it about a periphery and setting the waypoints one-by-one, and to rapidly take GPS coordinates to indicate the exact position of the animal at all times.
In one embodiment, the present invention provides for the use of a multi-axis accelerometer to adjust for lag or error of the GPS to more precisely determine the animal""s location; to increase the GPS accuracy for use in a containment application; to provide an animal containment system which requires minimal labor to set up; to provide a inexpensive solution to animal containment; and to provide for an aesthetically-pleasing animal containment solution.